Method and apparatus for cooling a turbomachinery blade

ABSTRACT

A turbomachinery blade operating at elevated temperature and in a strong centrifugal field is cooled by a coolant loop located within the blade constituting an open, mixed convection, thermosyphon system utilizing water as the coolant and establishing density differentials in the coolant within the loop by injecting cooler water into one portion of the loop and extracting coolant fluid from another portion of the loop to maintain system pressure and coolant mass at desired levels to thereby establish continuous coolant recirculation within the coolant loop.

0 United States Patent 1 [111 3,902,819

Holchendler et a1. Sept. 2, 1975 [54] METHOD AND APPARATUS FOR COOLING3,550,372 12/1970 Craig 416/95 X A TURBOMACHINERY BLADE 3,623,82511/1971 Schneider 416/96 [75] Inventors: Jacob l-Iolchendler, EastHartford; REI N PATENT OR APPLICATIONS David J p Manchester; William879,485 6/1953 Germany 416/96 F. Laverty; James J. Wesbecher, 783,1779/1957 United Kingdom. 416/96 both of Glastonbury, all of Conn. 237,4759/1945 Switzerland 416/96 774,499 5/1957 United Kingdom 416/96 [73]Assignee: United Aircraft Corporation, East Hartford, Conn. OTHERPUBLICATIONS [22] Filed: June 4, 1973 The Oil Engine and Gas Turbine,Feb. 1958, pp.

396398. [21] Appl. No.: 367,052

Primary Examiner-Everette A. Powell, Jr. [52] US. Cl. 416/1; 416/96;416/97 Attorney, Agent, or FirmVernon F. l-Iauschild [51] Int. Cl...F01D 5/18 [58] Field of Search 416/9597,

416/92, 96 A, 97 A, 1; 415/114, 115, 1 [57] ABSTRACT A turbomachineryblade operating at elevated temper- [56] R fere es Ci d ature and in astrong centrifugal field is cooled by a UNITED STATES PATENTS coolantloop located within the blade constituting an open, mixed convection,thermosyphon system utiliz- ,708,564 5/1955 Erickson 416/96 g watar asthe coolant and establishing dnsity ,737,366 3/1956 Ledinegg 416/962,744723 5/l956 Roush I 415,114 ferentlals 1n the coolant within theloop by in ecting 2,750147 6/1956 Smith 416/96 cooler water into oneportion of the loop and extract- 2763427 9/1956 Lindsey 41 97 ingcoolant fluid from another portion of the loop to 2,778,601 1 1957Eckert 416/96 maintain system pressure and coolant mass at desired2,839,26 58 Allen 4l6/96 levels to thereby establish continuous coolantrecircu- 2,883,l51 4/1959 Dolida 416/96 l i i hi th Coolant 3,045,9657/1962 Bowmer 416/97 UX 3,1 10,473 11/1963 Frank et a1. 416/1 19 Claims,3 Drawing Figures METHOD AND APPARATUS FOR COOLING TURBOMACI-IINERYBLADE BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to turbomachinery blades, such as turbine blades, andmore particularly to method and apparatus for cooling such blades.

2. Description of the Prior Art In the turbomachinery blade cooling art,thermosyphon systems have been used previously. In Ledinegg U.S. Pat.No. 2,667,326, a closed loop thermosyphon cooling system is used,however, the coolant is evaporated in a single pass through the turbineblade, and thence is returned to a remote heat sink in theturbomachinery disc for condensation prior to recirculation through theturbine blades. Also, geometric separation of the coolant inlet andoutlet from the blades is made possible only by the presence ofdifferent phases at the inlet and the outlet. Eckert U.S. Pat. No.2,778,601 teaches a thermosyphon blade cooling system which is open loopand utilizes water as its cooling fluid, however, the system is singlepass and the cooling media is passed through the turbine blade but asingle time and is then discharged overboard. In addition, no specialeffort is made to deliberately define and separate the inlet and exitcoolant flow location. Bruckmann U.S. Pat. No. 2,779,565 is similar toEckert, albeit air is used as the cooling media but in single-passfashion. Schneider U.S. Pat. No. 3,623,825 utilizes liquid metal,without phase change. in aparticular portion of a heat exchanger withinthe blade in a sealed compartment and thereby presents sealing,maintainability, and weight problems. These single pass systems areinefficient and the systems utilizing heat sinks remote from the bladeare unnecessarily complicated and heavy.

SUMMARY OF THE INVENTION A primary object of the present invention is toprovide an improved method and hardware for cooling turbomachineryblading utilizing an open, mixed convection thermosyphon system withinthe blade.

In accordance with the present invention, the turbomachinery bladecoolant is preferably steam at high pressure and at temperature abovecritical, into which coolant at low temperature, and high pressure isinjected in order to create a concentrated heat sink and therebyestablish a density differential so as to produce continuousthermosyphon multi-pass pumping of the coolant.

In accordance with a further aspect of the present invention, a selectedamount of cooling fluid is discharged from the system at the same rateat which the low temperature coolant is added to the system to maintainsystem pressure and coolant mass at a selected level. During transientoperating conditions, the

inlet and exit flow rates may differ.

It is still a further important teaching of this invention that thecoolant flow within the blade is at a rate many times as great(frequently tenfold or more) as the rate of injection of low temperaturecoolant thereby minimizing the variation of coolant temperature in thedifferent parts of the blade, giving a high heat transfer coefficient asrequired to cool the blade while avoiding the problems associated withchange of phase (particularly boiling), and making the cooling systemthermodynamically efficient.

It is a very important feature of this invention that the coolant isrecirculated within the blade without the need for having heattransferred from the coolant prior to recirculation.

An advantage of this system is that water may be used as the coolant,and therefore our system may use a coolant which has good thermalproperties, ready availability especially in stationary and marineinstallations, which is economical, and which requires no specialhandling, as is the case with many other coolants.

It is a further important feature of this blade cooling system that theheat sink is positioned solely within the blade, and bears norelationship to the supporting disc or other related turbomachinery.

It is a further feature of this invention that the turbomachinery bladebe fabricated so as to include a coolant loop therewithin comprising anouter header extending substantially along the blade tip, an innerheader extending substantially along the blade root, and passages orconduits extending between the headers, and further preferably includinga blade trailing edge header and a discharge passage or passages joinedto the main coolant loop through an orifice so as to permit theextraction of fluid from the cooling loop in a selective fashion so asto maintain system pressure and fluid mass at desired levels and toregulate the mixing process at the inlet location.

According to another feature of our invention, the fluid extracted fromthe system is used for cooling purposes, and preferably to cool theblade trailing edge.

It is a further feature of this invention to teach a unique coolant loopfor a turbomachinery blade in which the coolant remains in asupercritical state as it goes through multiple passes throughout theloop.

Other objects and advantages of the present invention may be seen byreferring to the following description and claims, read in conjunctionwith the accompanying drawings. 1

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a showing of turbomachineryutilizing this invention.

FIG. 2 is a cross-sectional drawing through a turbo machinery bladeutilizing the present invention but the number of coolant passages havebeen reduced to better permit description.

FIG. 3 is a view taken along line 3-3 of FIG. 2 and shows arepresentative number of coolant passages.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 we seeturbomachinery unit 1, which may be a gas or steam turbine orcompressor, and which comprises at least one rotor 2 mounted forrotation about axis 3 and including a disc 4 supporting a plurality ofblades 10 about the periphery thereof. Rotor 2 is mounted within housing5, from which vaned stator 6 projects to control the angle of entry ofthe gas flowing through turbomachinery 1 as it approaches blades 10. x

Referring to FIGS. 2 and 3 we see turbomachinery blade 10, whichincludes blade tip 12, blade root 14, leading edge 16, trailing edge 18,and airfoil portion 20 extending between root l4 and tip 12. Blade 10 isadapted to be supported from a rotor disc 2 of a turbomachinerycompressor or turbine, for example, to be rotated therewith duringturbine engine operation and to have hot gases passed thereover so thatthe blade is operating both in a high temperature environment and astrong centrifugal force environment. For a more complete description ofan illustration of a turbomachinery blade and its associated turbineand/or compressor parts, reference may be had to US. Pat. Nos. 2,711,631and 2,747,367.

Blade 10 is fabricated so that coolant loop 22 is positioned therewithinand includes outboard header 24 extending along the blade tip 12,inboard header 26 extending along the blade root l4, and outflow passage28 and inflow heat exchanger passages extending between these headersand with passages 30 located adjacent to the blade convex and concavesurfaces 29 and 31. The cooling system also includes blade trailing edgeheader 32 which communicates with inboard header 26 through chokedorifice 34, and which communicates with the gas flow passage external ofblade 10 through a plurality of apertures 36 extending along and throughthe blade trailing edge 18. Coolant pressure and temperature levels inloop 22 are controlled by the sizing of orifice 34. Orifice 34 ispreferably adjacent to inner header 26 but could be adjacent to outerheader 28. Blade 10 may be fabricated in any convenient fashion, forexample, blade outer portion 38, which includes blade tip 12 and airfoilsection 20 may serve as a blade wall member into which blade internalportion may extend in projecting from root 14 in blade-Scabbard fashion,thereby defining those passages enumerated above the blade outer portion38 and blade inner portion would be sealably connected by welding or thelike.

The preferred cooling fluid in coolant passage 22 is water in the formof steam operating at supercritical temperature and pressure to form anopen, mixed convection-thermosyphon cooling system. This supercriticalsteam passes outwardly from inboard header 26 through passage 28 tooutboard header 24 and therefrom inwardly through passages 30 to inboardheader 26 and recirculation again outwardly through passage 28 inmulti-pass fashion. Preferably, passage 28 is located in a centralportion of the blade while the heat exchanger passages 30 are locatednear the blade outer surfaces 29 and 31. The motive force to create thiscirculation is derived from the heat sink positioned near the blade root14 in passage 28, specifically at the end of tube member 42 throughwhich water, at supercritical pressure but at a temperature lower thanthe supercritical steam is injected into the inner end of passage 28.The mixing of this low temperature coolant from conduit 42 serves tolower the temperature of the coolant in conduit 28 below the temperatureof the coolant in conduits 30 to establish both a temperature anddensity differential therebetween, thereby establishing a continuingflow of the coolant in cooling fluid system 22 outwardly through passage28 into outer header 24, and then inwardly through passages 30 to innerheader 26, and continued recirculation through this route as desired toeffect blade'cooling. To maintain the system fluid at desired pressureand total mass, a selected amount of coolant is discharged throughorifice 34 into blade trailing edge header 32, from which it isdischarged to gas flow path 35 through blade trailing edge apertures 36for the purpose of cooling the blade trailing edge. Orifice 34 is sizedso that the rate of coolant so discharged is at the same flow rate atwhich the low temperature coolant is entering the system through conduit42. Low temperature coolant for conduit 42 may be stored and/or suppliedin any convenient fashion, such as within or from the rotor disc 2. Inthis fashion, an open, mixed convention thermosyphon cooling system isestablished. This system therefore effects coolant (supercritical steam)recirculation by low temperature coolant (water) injection and thisprovides a uniqueness to our system over other known thermosyphonsystems in that our system establishes a flow rate in coolant which ison the order of 10 times as great as the flow rate of the injected lowtemperature coolant and this has the advantages of minimizing thevariation of coolant temperature in the different parts of blade 10,giving the high heat transfer coefficients required to cool the bladewhile avoiding the problems associated with change of phase of thecoolant, particularly boiling, and making the cooling systemthermodynamically efficient.

The present coolant system is said to be open because the coolant fluidis being discharged from the system through trailing edge ports 36, issaid to be mixed convection since the system operates by both free andforced convection, and is said to be a thermosyphon because thecontinuous pumping and recirculation of the coolant is brought about bythe functioning of the heat sink to establish density differentialswithin the cooling system 22.

In the present invention, the heat added to blade 10 during operationfor given external (gas-side) conditions, is proportional to thetemperature level and flow rate of the recirculating coolant which isproportional in turn, to the flow rate of injected coolant. It willtherefore be seen that this system functions as a convective (orthermal) amplifier.

The three main elements of this blade cooling system are: (l) a coolantloop 22 within the blade 10, (2) a low temperature coolant injectionsystem (conduit 42) which is used to produce the pumping force tocirculate the coolant in the loop 22, and (3) a discharge orifice system32-36 to exhaust spent coolant to the turbomachinery gas path andmaintain the required coolant pressure and mass level in the blade. Thecooling of the blade is primarily accomplished by the transfer of heatto the supercritical water flowing radially inwardly through the heatexchanger passages 30 By way of explanation of the operation of thissystem on the thermosyphon principle, let us assume that supercriticalsteam in inner header 26 is at 950F, and that water at F is introducedthereinto through conduit 42 in the lower part of outflow passage 28 soas to produce a mixed temperature therein of 900F. This 900 water willflow into tip header 24 and then flow back to the inner header 26through exchanger tubes or passages 30 wherein heat transfer from thepassage walls causes the supercritical steam to be elevated to the 950temperature by the time it reaches inner header 26. It will therefore beseen that the mean or average temperature of the supercritical steam inthe heat exchanger passages 30 is 925 and that the temperature of thesupercritical steam in passage 28 is 900, giving a 25F temperaturedifferential. This temperature differential produces a densitydifferential so that the more dense supercritical steam at 900 will beacted upon to a greater degree by the centrifugal force generated by therotating rotor 2 than the less dense supercritical steam in heatexchanger conduits 30, thereby establishing the pumping force action ofthe thermosyphon principle which will cause the fluid to so continue tocirculate through coolant loop 22, so long as this temperaturedifferential, and hence the density differential, is maintained. Tomaintain this temperature differential, the cool water at 100F iscontinuously injected into the inner end of passage 28 and supercriticalsteam is discharged from the system at an equal rate to maintain thepressure and mass of the coolant in loop 22 at desired levels. To obtainmaximum benefit from the supercritical steam being discharged from thesystem, we pass that steam through the trailing edge header and out thetrailing edge of the blade so that it cools the trailing edge of theblade.

lt is important to note that in our construction the cooling fluid(steam) can be held totally in the supercritical range at all timesthroughout its many passes through the cooling loop, thereby avoidingboiling problems. A second advantage of operation in the supcrcriticalrange is that the operating temperature is high enough so thatovercooling the blade does not occur which would extract too much heatfrom the gas flowing over the blade and diminish the cycle efficiency.However, we are maintaining the blade cool enough to insure itsstructural integrity.

We wish it to be understood that we do not desire to be limited to theexact details of construction shown and described, for obviousmodifications will occur to a person skilled in the art.

We claim:

1. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas pass thereover so as to thereby be subjected to bothcentrifugal force and high temperature including:

1. a coolant loop within the blade,

2. a cooling fluid filling said loop,

3. heat sink establishing means acting upon the cooling fluid in oneportion of said loop to establish a temperature and hence a densitydifferential between the cooling fluid in different parts of saidcoolant loop to thereby establish a continuous cir culatory flow andrecirculation of cooling fluid within the coolant loop utilizing thethermal syphon principle, and

4. wherein said heat sink establishing means comprises a means forinjecting a coolant at lesser temperature than the cooling fluid intosaid coolant loop at a selected location, and means to discharge coolingfluid from the coolant loop at the same rate that coolant is beinginjected into the coolant loop to thereby maintain selected pressurelevel and coolant mass in the coolant loop.

2. A blade according to claim 1 wherein the cooling fluid is steam abovecritical temperature and pressure and wherein the coolant is water abovecritical pressure and at low temperature.

3. A blade according to claim 2 wherein the fluid extracted from thecoolant loop is discharged through the blade walls.

4. A blade according to claim 3, which blade has discharged slots in theblade trailing edge and wherein the fluid is discharged through saidtrailing edge slots.

5. A blade according to claim 1 wherein said blade comprises an outercover defining the blade tip and airfoil section walls and an innermember inserted thereinto in blade-in-scabbard fashion and sealablyconnected thereto. with both the blade outer cover portion and the bladeinner portion being selectively shapedto define said coolant loop.

6. A blade according to claim 1 and including means to control coolantcirculation rate and temperature,

5 rate of heat removal from and the temperature of the blade.

7. A blade according to claim 1 and including means to control theamount of coolant discharged from the coolant loop.

8. The method of cooling a turbomachinery blade utilizing thethermosyphon principle including the steps of: i

1. providing a plurality of substantially radially extending passages inthe blade interior joining a header extending along the blade tip and aheader extending along the blade root,

2. filling said passages with fluid which will be in the supercriticalstate at blade operating conditions, and i 3. establishing a densitydifferential between the fluid in at least one of said passages and thefluid in'the remaining passages to establish continuous circulation andrecirculation of fluid radially inwardly through the passages having theless dense fluid and radially outwardly through the passage having themore dense fluid to thereby cool the blade.

9. A turbomachinery blade adopted to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adopted to be connected to the blade disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a selectively shaped passage systemincluding a series of substantially radially extending passage joiningan outboard header and an inboard header,

3. a blade tip located at the end of the blade airfoil sectionoppositeto the blade root,

4. a fluid which will operate at a supercritical state at bladeoperatingconditions, and

5. means to establish a density differential in the fluid in saidpassages'and thereby establish continuous circulatory flow of said fluidradially outwardly through at least one of said radial passages, throughsaid outboard header, radially inwardly through at least oneof saidradial passages and said inboard header in multi-pass, recirculationfashion.

10. The method of cooling a turbomachinery blade utilizing thethermosyphon principle including the steps 1. providing a plurality ofsubstantially radially extending passages in the blade interior joininga header extending along the blade tip and a header extending along theblade root,

2. filling said passages with fluid.

3. establishing a density differential between the fluid in at least oneof said passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade. and

wherein said last step includes cooling the temperature of the fluid inat least one of the passages by direct heat sink injection to increaseits density so that, in accordance with the thermosyphon principle, themore dense fluid will flow radially outwardly to the tip header and theless dense fluid will flow radially inwardly to the root headerestablish blade coolant circulation.

11. The method of cooling a turbomachinery blade utilizing thethermosyphon principle including the steps of:

1. providing a plurality of substantially radially extending passages inthe blade interior joining a header extending along the blade tip and aheader extending along the blade root,

2. filling said passages with fluid,

3. establishing a density differential between the fluid in at least oneof said passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade, and

wherein the cooling fluid is supercritical and wherein water at atemperature less than the supercritical is introduced to one of thepassages to establish a heat sink to produce the desired densitydifferential, and wherein supercritical steam is bled from the system atthe same rate that cooling water is added to the system to maintain thecoolant mass pressure, and the density differential substantiallyconstant in the system.

12. The method-of cooling a turbomachinery blade utilizing thethermosyphon principle including the steps of:

1. providing a plurality of substantially radially extending passages inthe blade interior joining a header extending along the blade tip and aheader extending along the blade root,

2. filling said passages with fluid,

3. establishing a density differential between the fluid in at least oneof said passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade, and

including the additional step of controlling the density differentialsso established in the fluid so as to control the recirculation rate ofthe cooling fluid in the passages, the operating temperatures of thefluid being circulated, the rate of heat removal from the blade into thecooling fluid, and blade metal temperature.

13. The method of cooling a turbomachinery blade utilizing thethermosyphon principle including the steps of:

1. providing a plurality of substantially radially extending passages inthe blade interior joining a header extending along the blade tip and aheader extending along the blade root,

2. filling said passages with fluid,

3. establishing a density differential between the fluid in at least oneof said passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade, and

troduced to one of the passages to establish a heat sink I to producethe desired density differential, and wherein supercritical steam isbled from the system at the same rate that cooling water is added to thesystem to maintain the coolant mass pressure, and the densitydifferential substantially constant in the system, and, further, whereinthe heat sink is positioned remote from the system bleed so as toachieve maximum effective mixing with single phase fluids and maintainconstant steady state circulation rates.

14. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adapted to be connected to the blade disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a passage system including a series ofsubstantially radially extending passages joining an outboard header andan inboard header,

3. a blade tip located at the end of the blade airfoil section oppositeto the blade root,

a fluid filling said headers and said passages for circulation therein,and

5. means to establish a density differential in the fluid in saidpassages and thereby establish continuous circulatory flow of said fluidradially outwardly through at least one of said radial passages, throughsaid outboard header, radially inwardly through at least one of saidradial passages and said inboard header in multi-pass, recirculationfashion, and

wherein said density differential establishing means ineluding:

1. means to inject a cooling fluid into one of said passages saidcooling fluid being at a lesser temperature than the temperature of thecirculating fluid in the other passages to thereby establish atemperature differential and hence a density differential therebetweenand thereby produce thermosyphon circulation and recirculation of fluidin the gravity field, and

2. means to extract fluid from said passage system at the same rate thatthe cooling fluid is being introduced to said passage system.

15. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adapted to be connected to the blade disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a passage system including a series ofsubstantially radially extending passages joining an outboard header andan inboard header,

3. a blade tip located at the end of the blade airfoil section oppositeto the blade root,

4. a fluid filling said headers and said passages for circulationtherein, and

5. means to establish a density differential in the fluid in saidpassages and thereby establish continuous circulatory flow of said fluidradially outwardly through at least one of said radial passages, throughsaid outboard header, radially inwardly through at least one of saidradial passages and said inboard header in multi-pass, recirculationfashion, and

wherein said density differential establishing means ineluding:

1. means to inject a cooling fluid into one of said passages saidcooling fluid being at a lesser temperature than the temperature of thecirculating fluid in the other passages to thereby establish atemperature differential and hence a density differential therebetweenand thereby produce thermosyphon circulation and recirculation of fluidin the gravity field, and

2. means to extract fluid from said passage system at the same rate thatthe cooling fluid is being introduced to said passage system, and,further,

wherein said blade has at least one aperture in the blade trailing edgeand wherein the extracted fluid is discharged through apertures in theblade trailing edge to cool the blade trailing edge.

16. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adapted'to be connected to the blade disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a passage system including a series ofsubstantially radially extending passages joining an outboard header andan inboard header,

3. a blade tip located at the end of the blade airfoil section oppositeto the blade root,

4. a fluid filling said headers and said passages for circulationtherein, and

5. means to establish a density differential in the fluid in saidpassages and thereby establish continuous circulatory flow of said fluidradially outwardly through at least one of said radial passages, throughsaid outboard header, radially inwardly through at least one of saidradial passages and said inboard header in multi-pass, recirculationfashion, and

wherein said density differential establishing means including:

1. means to inject a cooling fluid into one of said passages saidcooling fluid being at a lesser temperature than the temperature of thecirculating fluid in the other passages to thereby establish atemperature differential and hence a density differential therebetweenand thereby produce thermosyphon circulation and recirculation of fluidin the gravity field, and

2. means to extract fluid from said passage system at the same rate thatthe cooling fluid is being introduced to said passage system, and,further,

wherein said blade has at least one aperture in the blade trailing edgeand wherein the extracted fluid is discharged through apertures in theblade trailing edge to cool the blade trailing edge, and, still further,wherein said fluid extraction means includes an orifice joining one ofsaid headers to a blade trailing edge header which is connected to thehot gas stream through said blade trailingedge apertures.

17. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adapted to be connected to the blade disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a passage system including a series ofsubstantially radially extending passages joining an outboard header andand inboard header,

a blade tip located at the end of the blade airfoil section opposite tothe blade root,

. a fluid filling said headers and said passages for circulationtherein, and

means to establish a density differential in the fluid in said passagesand thereby establish continuous circulatory flow of said fluid radiallyoutwardly through at least one of said radial passages, through saidoutboard header, radially inwardly through at least one of said radialpassages and said inboard header in mulit-pass, recirculation fashion,and wherein said density differential establishing means including:

1. means to inject a cooling fluid into one of said passages saidcooling fluid being at a lesser temperature than the temperature of thecirculating fluid in the other passages to thereby establish atemperature differential and hence a density differential therebetweenand thereby produce thermodyphon circulation and recirculation of fluidin the gravity field, and

2. means to extract fluid from said passage system at the same rate thatthe cooling fluid is being introduced to said passage system, and,further,

wherein said blade has at least one aperture in the blade trailing edgeand wherein the extracted fluid is discharged through apertures in theblade trailing edge to cool the blade trailing edge, and, still further,wherein said fluid extraction means includes an orifice joining one ofsaid headers to a blade trailing edge header which is connected to thehot gas stream through said blade trailing edge apertures, and whereinsaid one header is the inboard header.

18. A turbomachinery blade adpated to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adapted to be connected to the blade disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a passage system including a series ofsubstantially radially extending passages joining an outboard header andan inboard header,

1 1 3. a blade tip located at the end of the blade airfoil sectionopposite to the blade root, 4. a fluid filling said headers and saidpassages for circulation therein, and

trailing edge header which is connected to the hot gas stream throughsaid blade trailing edge apertures, and wherein said orifice is causedto operate in chocked condition.

disc,

2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially out- 5. means to establish a density differential in the fluid5 dl therefrom h h bl d i mounted on in said passages and therebyestablish continuous the disc and shaped to define therewithin a passageCirculatory flow of said fluld radially outwardly system including aseries of substantially radially through at least one of Said radialPassages through extending passages joining an outboard header and saidoutboard header, radially inwardly through at an inboard headerI leastone of Said radial Passages and Said inboard 3. a blade tip located atthe end of the blade airfoil header in multi-pass, recirculationfashion, and Section Opposite to the blade rOOtI wherein said densitydifferential establishing means ina fluid fining said headers and Saidpassages for sip cludmg: I I I I I culation therein, and

means 9 a coolmg l mto one of smd 5. means to establish a densitydifferential in the fluid Sages coolmg fluld bemg at a lesser tempera insaid passages and thereby establish continuous ture than the temperatureof the circulating fluid in Circulatory flow of said fluid radiallyoutwardly the other passfiges to thereby csmbllsh through at least oneof said radial passages, through ture dlfferentlal and hence a densltydlfferentlal Said Outboard headerI radially inwardly through attherebeiween and .therebyproduce. thermosyphim least one of said radialpassages and said inboard clrculatlon and reclrculatlon of fluld m thegravity 2 header In multi pass recirculafion fashion and 2 field and I II wherein said density differential establishing means inmeans toextract fluld from sald passage system at the same rate that the coolingfluid is being introcludmg: duced to said passage system, and, further,wherein means 9 mjecl a coolmg fluld one of Sald passaid blade has atleast one aperture in the blade Sages Coolmg fluld being f f" trailingedge and wherein the extracted fluid is ture than the temperature of theclrculatlng fluld in charged through apertures in the blade trailing theother passages to thereby stabl sh a temper aedge to cool the bladetrailing edge andI still ture dlfferentlal and hence a densltydlfferentlal ther, wherein said fluid extraction means includestherebetweeen and thereby Produce thermosyphon an orifice joining one ofsaid headers to a blade circulation and recirculation of fluid in thegravity field, and

2. means to extract fluid from said passage system at the same rate thatthe cooling fluid is being introduced to said passage system, and

wherein said system circulatory fluid is steam above critical pressureand temperature and wherein said lower temperature cooling fluid iswater above critical pressure and at low temperature.

19. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas passed thereover so as to thereby be subjected bothto centrifugal force and high temperature including:

1. a blade root adapted to be connected to the blade

1. A turbomachinery blade adapted to be mounted for rotation on a discand to have hot gas pass thereover so as to thereby be subjected to bothcentrifugal force and high temperature including:
 1. a coolant loopwithin the blade,
 2. a cooling fluid filling said loop,
 3. heat sinkestablishing means acting upon the cooling fluid in one portion of saidloop to establish a temperature and hence a density differential betweenthe cooling fluid in different parts of said coolant loop to therebyestablish a continuous circulatory flow and recirculation of coolingfluid within the coolant loop utilizing the thermal syphon principle,and
 4. wherein said heat sink establishing means comprises a means forinjecting a coolant at lesser temperature than the cooling fluid intosaid coolant loop at a selected location, and means to discharge coolingfluid from the coolant loop at the same rate that coolant is beinginjected into the coolant loop to thereby maintain selected pressurelevel and coolant mass in the coolant loop.
 2. a cooling fluid fillingsaid loop,
 2. A blade according to claim 1 wherein the cooling fluid issteam above critical temperature and pressure and wherein the coolant iswater above critical pressure and at low temperature.
 2. filling saidpassages with fluid which will be in the supercritical state at bladeoperating conditions, and
 2. a blade airfoil section shaped to definethe blade tip, the blade leading edge and trailing edge and attached tothe blade root to extend radially outwardly therefrom when the blade ismounted on the disc and shaped to dEfine therewithin a passage systemincluding a series of substantially radially extending passages joiningan outboard header and an inboard header,
 2. means to extract fluid fromsaid passage system at the same rate that the cooling fluid is beingintroduced to said passage system.
 2. means to extract fluid from saidpassage system at the same rate that the cooling fluid is beingintroduced to said passage system, and, further, wherein said blade hasat least one aperture in the blade trailing edge and wherein theextracted fluid is discharged through apertures in the blade trailingedge to cool the blade trailing edge, and, still further, wherein saidfluid extraction means includes an orifice joining one of said headersto a blade trailing edge header which is connected to the hot gas streamthrough said blade trailing edge apertures.
 2. a blade airfoil sectionshaped to define the blade tip, the blade leading edge and trailing edgeand attached to the blade root to extend radially outwardly therefromwhen the blade is mounted on the disc and shaped to define therewithin apassage system including a series of substantially radially extendingpassages joining an outboard header and and inboard header,
 2. a bladeairfoil section shaped to define the blade tip, the blade leading edgeand trailing edge and attached to the blade root to extend radiallyoutwardly therefrom when the blade is mounted on the disc and shaped todefine therewithin a passage system including a series of substantiallyradially extending passages joining an outboard header and an inboardheader,
 2. means to extract fluid from said passage system at the samerate that the cooling fluid is being introduced to said passage system,and, further, wherein said blade has at least one aperture in the bladetrailing edge and wherein the extracted fluid is discharged throughapertures in the blade trailing edge to cool the blade trailing edge,and, still further, wherein said fluid extraction means includes anorifice joining one of said headers to a blade trailing edge headerwhich is connected to the hot gas stream through said blade trailingedge apertures, and wherein said one header is the inboard header. 2.means to extract fluid from said passage system at the same rate thatthe cooling fluid is being introduced to said passage system, and,further, wherein said blade has at least one aperture in the bladetrailing edge and wherein the extracted fluid is discharged throughapertures in the blade trailing edge to cool the blade trailing Edge,and, still further, wherein said fluid extraction means includes anorifice joining one of said headers to a blade trailing edge headerwhich is connected to the hot gas stream through said blade trailingedge apertures, and wherein said orifice is caused to operate in chockedcondition.
 2. a blade airfoil section shaped to define the blade tip,the blade leading edge and trailing edge and attached to the blade rootto extend radially outwardly therefrom when the blade is mounted on thedisc and shaped to define therewithin a passage system including aseries of substantially radially extending passages joining an outboardheader and an inboard header,
 2. a blade airfoil section shaped todefine the blade tip, the blade leading edge and trailing edge andattached to the blade root to extend radially outwardly therefrom whenthe blade is mounted on the disc and shaped to define therewithin apassage system including a series of substantially radially extendingpassages joining an outboard header and an inboard header,
 2. fillingsaid passages with fluid,
 2. filling said passages with fluid, 2.filling said passages with fluid,
 2. filling said passages with fluid,2. a blade airfoil section shaped to define the blade tip, the bladeleading edge and trailing edge and attached to the blade root to extendradially outwardly therefrom when the blade is mounted on the disc andshaped to define therewithin a selectively shaped passage systemincluding a series of substantially radially extending passage joiningan outboard header and an inboard header,
 2. means to extract fluid fromsaid passage system at the same rate that the cooling fluid is beingintroduced to said passage system, and, further, wherein said blade hasat least one aperture in the blade trailing edge and wherein theextracted fluid is discharged through apertures in the blade trailingedge to cool the blade trailing edge.
 2. a blade airfoil section shapedto define the blade tip, the blade leading edge and trailing edge andattached to the blade root to extend radially outwardly therefrom whenthe blade is mounted on the disc and shaped to define therewithin apassage system including a series of substantially radially extendingpassages joining an outboard header and an inboard header,
 2. means toextract fluid from said passage system at the same rate that the coolingfluid is being introduced to said passage system, and wherein saidsystem circulatory fluid is steam above critical pressure andtemperature and wherein said lower temperature cooling fluid is waterabove critical pressure and at low temperature.
 3. a blade tip locatedat the end of the blade airfoil section opposite to the blade root, 3.establishing a density differential between the fluid in at least one ofsaid passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade, and wherein said last step includes cooling the temperature ofthe fluid in at least one of the passages by direct heat sink injectionto increase its density so that, in accordance with the thermosyphonprinciple, the more dense fluid will flow radially outwardly to the tipheader and the less dense fluid will flow radially inwardly to the rootheader establish blade coolant circulation.
 3. a blade tip located atthe end of the blade airfoil section opposite to the blade root, 3.establishing a density differential between the fluid in at least one ofsaid passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade, and including the additional step of controlling the densitydifferentials so established in the fluid so as to control therecirculation rate of the cooling fluid in the passages, the operatingtemperatures of the fluid being circulated, the rate of heat removalfrom the blade into the cooling fluid, and blade metal temperature. 3.establishing a density differential between the fluid in at least one ofsaid passages and the fluid in the remaining passages to establishcontinuous circulation and recirculation of fluid radially inwardlythrough the passages having the less dense fluid and radially outwardlythrough the passage having the more dense fluid to thereby cool theblade, and wherein the cooling fluid is supercritical and wherein waterat a temperature less than the supercritical is introduced to one of thepassages to establish a heat sink to produce the desired densitydifferential, and wherein supercritical steam is bled from the system atthe same rate that cooling water is added to the system to maintain thecoolant mass pressure, and the density differential substantiallyconstant in the system.
 3. establishing a density differential betweenthe fluid in at least one of said passages and the fluid in theremaining passages to establish continuous circulation and recirculationof fluid radially inwardly through the passages having the less densefluid and radially outwardly through the passage having the more densefluid to thereby cool the blade, and wherein the cooling fluid issupercritical and wherein water at a temperature less than thesupercritical is introduced to one of the passages to establish a heatsink to produce the desired density differential, and whereinsupercritical steam is bled from the system at the same rate thatcooling water is added to the system to maintain the coolant masspressure, and the density differential substantially constant in thesystem, and, further, wherein the heat sink is positioned remote fromthe system bleed so as to achieve maximum effective mixing with singlephase fluids and maintain constant steady state circulation rates.
 3. ablade tip located at the end of the blade airfoil section opposite tothe blade root,
 3. a blade tip located at the end of the blade airfoilsection opposite to the blade root,
 3. a blade tip located at the end ofthe blade airfoil section opposite to the blade root,
 3. a blade tiplocated at the end of the blade airfoil section opposite to the bladeroot,
 3. establishing a density differential between the fluid in atleast one of said passages and the fluid in the remaining passages toestablish continuous circulation and recirculation of fluid radiallyinwardly through the passages having the less dense fluid and radiallyoutwardly through the passage having the more dense fluid to therebycool the blade.
 3. a blade tip located at the end of the blade airfoilsection opposite to the blade root,
 3. A blade according to claim 2wherein the fluid extracted from the coolant loop is discharged throughthe blade walls.
 3. heat sink establishing means acting upon the coolingfluid in one portion of said loop to establish a temperature and hence adensity differential between the cooling fluid in different parts ofsaid coolant loop to thereby establish a continuous circulatory flow andrecirculation of cooling fluid within the coolant loop utilizing thethermal syphon principle, and
 4. wherein said heat sink establishingmeans comprises a means for injecting a coolant at lesser temperaturethan the cooling fluid into said coolant loop at a selected location,and means to discharge cooling fluid from the coolant loop at the samerate that coolant is being injected into the coolant loop to therebymaintain selected pressure level and coolant mass in the coolant loop.4. A blade according to claim 3, which blade has discharged slots in theblade trailing edge and wherein the fluid is discharged through saidtrailing edge slots.
 4. a fluid filling said headers and said passagesfor circulation therein, and
 4. a fluid filling said headers and saidpassages for circulation therein, and
 4. a fluid filling said headersand said passages for circulation therein, and
 4. a fluid filling saidheaders and said passages for circulation therein, and
 4. a fluidfilling said headers and said passages for circulation therein, and
 4. afluid which will operate at a supercritical state at blade operatingconditions, and
 4. a fluid filling said headers and said passages forcirculation therein, and
 5. means to establish a density differential inthe fluid in said passages and thereby establish continuous circulatoryflow of said fluid radially outwardly through at least one of saidradial passages, through said outboard header, radially inwardly throughat least one of said radial passages and said inboard header inmulti-pass, recirculation fashion, and wherein said density differentialestablishing means including:
 5. means to establish a densitydifferential in the fluid in said passages and thereby establishcontinuous circulatory flow of said fluid radially outwardly through atleast one of said radial passages, through said outboard header,radially inwardly through at least one of said radial passages and saidinboard header in multi-pass, recirculation fashion.
 5. means toestablish a density differential in the fluid in said passages andthereby establish continuous circulatory flow of said fluid radiallyoutwardly through at least one of said radial passages, through saidoutboard header, radially inwardly through at least one of said radialpassages and said inboard header in multi-pass, recirculation fashion,and wherein said density differential establishing means including: 5.means to establish a density differential in the fluid in said passagesand thereby establish continuous circulatory flow of said fluid radiallyoutwardly through at least one of said radial passages, through saidoutboard header, radially inwardly through at least one of said radialpassages and said inboard header in multi-pass, recirculation fashion,and wherein said density differential establishing means including: 5.means to establish a density differential in the fluid in said passagesand thereby establish continuous circulatory flow of said fluid radiallyoutwardly through at least one of said radial passages, through saidoutboard header, radially inwardly through at least one of said radialpassages and said inboard header in mulit-pass, recirculation fashion,and wherein said density differential establishing means including: 5.means to establish a density differential in the fluid in said passagesand thereby establish continuous circulatory flow of said fluid radiallyoutwardly through at least one of said radial passages, through saidoutboard header, radially inwardly through at least one of said radialpassages and said inboard header in multi-pass, recirculation fashion,and wherein said density differential establishing means including: 5.means to establish a density differential in the fluid in said passagesand thereby establish continuous circulatory flow of said fluid radiallyoutwardly through at least one of said radial passages, through saidoutboard header, radially inwardly through at least one of said radialpassages and said inboard header in multi-pass, recirculation fashion,and wherein said density differential establishing means including:
 5. Ablade according to claim 1 wherein said blade comprises an outer coverdefining the blade tip and airfoil section walls and an inner memberinserted thereinto in blade-in-scabbard fashion and sealably connectedthereto, with both the blade outer cover portion and the blade innerportion being selectively shaped to define said coolant loop.
 6. A bladeaccording to claim 1 and including means to control coolant circulationrate and temperature, rate of heat removal from and the temperature ofthe blade.
 7. A blade according to claim 1 and including means tocontrol the amount of coolant discharged from the coolant loop.
 8. Themethod of cooling a turbomachinery blade utilizing the thermosyphonprinciple including the steps of:
 9. A turbomachinery blade adopted tobe mounted for rotation on a disc and to have hot gas passed thereoverso as to thereby be subjected both to centrifugal force and hightemperatUre including:
 10. The method of cooling a turbomachinery bladeutilizing the thermosyphon principle including the steps of:
 11. Themethod of cooling a turbomachinery blade utilizing the thermosyphonprinciple including the steps of:
 12. The method of cooling aturbomachinery blade utilizing the thermosyphon principle including thesteps of:
 13. The method of cooling a turbomachinery blade utilizing thethermosyphon principle including the steps of:
 14. A turbomachineryblade adapted to be mounted for rotation on a disc and to have hot gaspassed thereover so as to thereby be subjected both to centrifugal forceand high temperature including:
 15. A turbomachinery blade adapted to bemounted for rotation on a disc and to have hot gas passed thereover soas to thereby be subjected both to centrifugal force and hightemperature including:
 16. A turbomachinery blade adapted to be mountedfor rotation on a disc and to have hot gas passed thereover so as tothereby be subjected both to centrifugal force and high temperatureincluding:
 17. A turbomachinery blade adapted to be mounted for rotationon a disc and to have hot gas passed thereover so as to thereby besubjected both to centrifugal force and high temperature including: 18.A turbomachinery blade adpated to be mounted for rotation on a disc andto have hot gas passed thereover so as to thereby be subjected both tocentrifugal force and high temperature including:
 19. A turbomachineryblade adapted to be mounted for rotation on a disc and to have hot gaspassed thereover so as to thereby be subjected both to centrifugal forceand high temperature including: